Collaborations to provide bio-statistical expertise continued on four major epidemiologic studies within DCEG: (1) the Agricultural Health Study, a prospective study of a cohort of 90,000 adults living on farms in Iowa and North Carolina to investigate potential disease risks associated with agricultural exposures; (2) the ALTS trial, a randomized trial to examine whether human papilloma virus DNA type can be used to determine the appropriate treatment for women with abnormal PAP smears; (3) a case-control study of brain cancer to examine a variety of occupational exposures as well as cellular phone use; and (4) a case-control study of childhood acute lymphoblastic leukemia examining electromagnetic fields and other residential exposures. Collaboration began on a prospective study of possible cancer risk in men exposed to radar during military service in the 1950s and on a case- control study of non-Hodgkins lymphoma to investigate possible causes for the unexplained secular increase in rates. A study of trends in childhood cancer incidence and mortality rates was completed. A study of calendar period and birth cohort trends in breast, ovarian, endometrial, and cervical cancer mortality rates in the United States revealed important similarities and differences in risk patterns, some of which require further study. A study of trends in breast cancer mortality rates in England and Wales revealed markedly different calendar period and birth cohort patterns of risk, and reasons for the difference in trends between the U.S. and the U.K. are being explored. Additional projects and studies for which assistance continues to be provided include: an Italian case-control study of melanoma evaluating the possible role that differences in DNA-repair capacity might play in determining risk; a study examining the clinical significance of different mutations in the RB1 gene in hereditary retinoblastoma patients; investigations to determine if the frequency of stable aberrations is related to chronic exposure to ionizing radiation in U.S. radiologic technologists or in workers at the Sellafield British Nuclear Fuels facility; a study examining possible associations between HLA type and myelopathy risk in persons infected with HTLV-1; an evaluation of the reliability of assessing exposure by viewing videotapes of work practices. Methods were developed to conduct an interim analysis of smoking prevalence and tobacco consumption to determine whether the American Stop Smoking Intervention Study (ASSIST) states are reducing smoking a a faster rate than the non ASSIST states. A two-stage analysis of smoking prevalence is being used to evaluate the effect of the ASSIST funding. A repeated measures random effects model is being used to determine if the time trend in tobacco consumption shows a faster reduction in the ASSIST states than in the non-ASSIST states. A series of analyses of the NHANES I Epidemiologic Followup Study cohort were performed to examine possible associations between alcohol consumption or male pattern baldness and prostate cancer risk and between physical activity and breast cancer risk. A study examining the effectiveness of training primary care physicians about the importance of nutritional activities in cancer prevention was completed.